Celestial immutability

As with many of the ideas on this list, celestial immutability was an idea first espoused by the great Ancient Greek thinkers, like Aristotle and Ptolemy. Because their observations of the heavens seemed to show little difference, they believed that the skies beyond the moon’s orbit never changed. It was not until the 16th century, when Tycho Brahe noticed a new star in the sky, that this theory was first challenged with concrete evidence. The appearance of a new star proved that the universe was not constant and that the notion of its immutability, which was widespread for around two millennia, was fundamentally flawed.